Multi-location television conference system and control apparatus

Abstract: In a multi-location television conference system that connects five locations A, B, C, D, and E, when speeches take place at the four locations A, B, C, and D at the same time, at a listening location E, images of all the speaking locations A, B, C, and D are displayed on one screen with four divided screen areas. On the other hand, at the speaking location A, images of the speaking locations B, c, and D and an image of the former speaking location E are displayed on one screen with four divided screen areas. In addition, when images of speaking locations are displayed, locations names thereof are also displayed. Thus, a television conference held at a plurality of locations at a time can be smoothly managed as with a real conventional conference.

Description: The present invention relates to a television conference system for use in a multi-location television conference (also called videoconferencing). In recent years, with the advent of ISDN (Integrated Services Digital Networks), digital networks have been widely used and television conference systems have become popular. The television conference systems transmit image data and sound data among remote locations so as to hold conferences. Conventional television conference systems transmit image data and sound data between two locations (namely, point-to-point connection). Recently, to more effectively hold conferences, a multi-location television conference system as shown in Fig. 1 has gained public attention. The needs of multi-location television conference systems result from geographical distribution of offices (such as main office, works, laboratories, sales offices) of companies. In this situation, so as to reduce cost and time necessary for transmitting information, people, and materials, television conferences have been held among television conference terminal units disposed at remote locations. Fig. 1 is a schematic diagram showing an overall construction of a multi-location television conference system that holds a television conference among conference rooms A, B, C, and D disposed at four locations. In the drawing, reference numerals 1 to 4 refer to television conference terminal units disposed at the four conference rooms. Reference numeral 10 refers to a multi-location control apparatus disposed at a center station. The television conference terminal units (that may be hereinafter referred to as terminal units) 1 to 4 each have a camera, a monitor, a microphone, an encoding unit, and so forth. Thus, the television conference terminal units each have input and output functions of image data and sound data. Image data and sound data of each conference room are sent to the center unit 10. The center unit 10 sends the image data and sound data to each of the television conference terminal units. The center unit 10 receives image data and sound data from all the conference rooms, mixes all the sound data, sends the mixed sound data to the television conference terminal units 1 to 4, and distributes the image data to all the television conference terminal units. In this multi-location television conference system, a monitor of the television conference terminal unit at each conference room (location) switches and displays images of other conference rooms (of at least one location). When a speaking location is detected, the image thereof is automatically displayed. Thus, the monitor of each conference room displays at least an image of a speaking location. (However, the monitor of a speaking location displays an image of a former speaking location.) A switching and displaying type multi-location control apparatus that distributes an image of one conference room to television conference terminal units of other conference rooms is known. This multi-location control apparatus can be easily introduced because the television conference terminal units for use with the point-to-point connection type television conference system can be used as they are. Thus, the switching and displaying type multi-location control apparatus has been widely developed and fabricated. Moreover, a multi-location control apparatus having new station (NS)/past station (PS) designating mode is known. Conventionally, an image switching operation in the NS/PS designating mode is automatically performed when the television conference terminal unit at each location is operated. Alternately, this operation is automatically performed when the multi-location control apparatus detects a speaking attendant. This function is referred to as the speaking attendant detecting function. With this function, the multi-location control apparatus distributes image data of the speaking location (NS) to the television conference terminal units at other locations. In addition, the multi-location control apparatus distributes the image data of the former speaking location (PS) to the television conference terminal unit at the speaking location (NS). Fig. 2 is a schematic diagram showing an example of the operation of the NS/PS designating mode. In this drawing, a multi-location control apparatus 20 is connected to television conference terminal units 12A, 12B, 12C, 12D, and 12E disposed at five locations of conference rooms A, B, C, D, and E through a network. In this television conference system, when an attendant speaks at the conference room A or an image switching and selecting operation for an image of the conference room A is performed at another conference room, the multi-location control apparatus 20 designates the conference room A to the NS mode and sends the image data of the conference room A to the television conference terminal units at other conference rooms B, C, D, and E (see a solid arrow of Fig. 2). In addition, the multi-location control apparatus 200 sends the image data of the conference room D that has been designated to the PS mode to the conference room A that has been designated to the NS mode (see a dotted arrow of Fig. 2). Fig. 3 is a block diagram showing an overall construction of a multi-location television conference system having a multi-location control apparatus 110 that automatically designates the conference rooms A, B, ..., and E to the NS/PS mode depending on detecting a speaking attendant and switches and controls image data to be distributed to the television conference terminal units 120A, 120B, ..., and 120E. As shown in Fig. 3, each of the television conference terminal units 120A to 120E comprises a plurality of microphones 121, a microphone mixer 122, a speaker 123, a sound control unit 124, a sound encoding and decoding unit (hereinafter referred to as sound CODEC) 125, a camera 126, a monitor 127, an image CODEC 128, and a multiplexing and demultiplexing unit (MUX/DMUX) 129. The microphones 121 are directed to attendants in a conference room. The microphone mixer 122 mixes outputs of the microphones 121. The speaker 123 outputs a sound of another television conference terminal unit 120. The sound control unit 124 performs an input/output sound switching operation, an echo removing operation, or the like so as to prevent the output sound of the speaker 123 from entering the microphones 121. The sound CODEC 125 encodes sound data received from the sound control unit 123 and decodes sound data sent to the sound control unit 123. The camera 126 photographs the entire scene of the conference room, attendants, and/or materials. The monitor 127 displays images of other conference rooms received from other television conference terminal units 120. The image CODEC 128 encodes image data photographed by the camera 126 and decodes encoded data to an image to be displayed on the monitor 127. The MUX/DMUX unit 129 multiplexes and demultiplexes an input signal and an output signal of the sound CODEC 125 and the image CODEC 128. The television conference terminal units 120A to 120E with the above-mentioned construction are connected to the multi-location control apparatus 110. The multi-location control apparatus 110 comprises a multiplexing and demultiplexing (MUX/DMUX) unit 111, a sound CODEC 112, a sound level comparator 113, a mixer 114, an image selecting unit 115, and a control unit 116. The MUX/DMUX unit 111 multiplexes and demultiplexes sound data and image data received from and sent to each of the television conference terminal units 120A to 120E. The sound CODEC 112 is connected to the MUX/DMUX unit 111. The sound level comparator 113 compares levels of sound signals received from the sound CODECs 112 of the television conference terminal units 120A to 120E. The mixer 114 mixes the sound signals compared by the comparator 113 and sends the mixed sound signal to the speaker 123 of each of the television conference terminal unit 120A to 120E through the sound CODEC 112 and the MUX/DMUX unit 111. The image selecting unit 140 selects image data demultiplexed by the MUX/DMUX unit 111 and sends the demultiplexed image data to the monitor 127 of each of the television conference terminal units 120A to 120E. The control unit 116 sends a selecting signal to the image selecting unit 140 corresponding to the compared result of the sound level comparator 113. In this related art reference, the levels of the microphones 121 of the television conference terminal units 120A to 120E are compared by the sound level comparator 113 of the multi-location control apparatus 110. The multi-location control apparatus 110 designates the television conference terminal unit that outputs the maximum sound level to the NS mode. The image selecting unit 140 selects image data received from the television conference terminal unit with the maximum sound level and distributes this image data to other television conference terminal units. Fig. 4 is a block diagram showing an inner construction of the image selecting unit 140. Image data of the conference rooms A, B, C, ..., and X at n locations are input to the input terminal 141. The image data are sent to an NS selecting unit 142 and a PS selecting unit 143 that select one from n alternatives. The NS selecting unit 142 and the PS selecting unit 143 receive a selecting signal from the control unit 116 and send image data of conference rooms that have been designated the n NS/PS selecting units 144A, 144B, 144C, ..., and 144X to the NS and PS modes. The output terminals of the NS/PS selecting units 144A, 144B, 144C, ... , and 144X are connected to respective image data output terminals 145 of the conference rooms A, B, C, ... , and X so as to select and output image data of the conference rooms that have been designated to the NS mode or PS mode. In the image selecting unit 140 with the above-mentioned construction, when the conference room A is designated to the NS mode and the conference room E is designated to the PS mode, the control unit 116 outputs a selecting signal of the image data of the conference room A to the NS selecting unit 142 and a selecting signal of the image data of the conference room E to the PS selecting unit 143. The NS selecting unit 142 and the PS selecting unit 143 select and output image data received from the conference rooms A and B to the NS/PS selecting units 144A, 144B, ... , and 144X. The NS/PS selecting unit 144A selects and outputs the image data of the conference room E, which has been designated the PS mode. The other NS/PS selecting units 144B, 144C, ... , and 144X receive image data of the conference room A, which has been designated to the NS mode, from the control unit 116 and selects and outputs the image data. Thus, the image of the conference room A, which has been designated to the NS mode, is displayed on the respective monitors at the conference rooms B, C, ... , and X, which have not been designated to the NS mode. On the other hand, the image of the conference room E, which has been designated to the PS mode, is displayed on the monitor at the conference room A, which has been designated to the NS mode. In the first related art reference, image data is displayed in a fixed display format regardless of the number of speaking locations. In other words, the number of images of speaking locations displayed on a monitor at each conference room does not vary. Thus, when the system displays an image of one location, even if there are a plurality of speaking locations, only an image of a main speaking location is displayed. On the other hand, when the system displays a plurality of locations at a time, even if there is one speaking location, divided screen images of listening locations are also displayed on the monitor. Thus, a listening attendant of a conference needs a time to knows who is speaking. In this situation, the reality of conference is deteriorated. The object of the present invention is to provide a display system that allows each attendant of a television conference to easily know speaking locations with reality. In the related art multi-location television conference system having the conventional MS/PS designating mode, when in conference rooms that have not been designated to the NS mode, a conference room is selected, since this selected conference room is designated to the NS mode, monitor images of other conference rooms are switched. On the other hand, in the system that automatically designates the NS mode when detecting a speaking attendant, whenever a speaking location (conference room) is changed, the monitor image data is automatically switched regardless of the intention of listening attendants. Thus, these attendants cannot continue to see images of other conference rooms other than those of speaking locations. Thus, in the conventional multi-location control apparatus with the designating NS/PS modes, attendants of other conference rooms cannot select images of conference rooms they want to see. When an attendant of another conference room changes the mode or speaks, the image thereof is automatically displayed on the monitor screens of other conference rooms. This automatic switching of images of conference rooms adversely affects the proceeding of the conference. IEEE INFOCOM'91 - The conference on computer communications - PROCEEDINGS vol. 3, 11 April 1991, BAL HARBOUR, FL, US pages 1127-1144 Tanigawa et al 'Personal Multimedia - Multipoint Teleconference System' discloses a system according to the preamble of claim 1 which allows teleconferences using voice, full-motion video and graphics to be established with up to twenty terminals through a mesh type multipoint configuration using broadband ISDN. In this system, each user has one video camera and can determine which facial images of the other participants will be displayed on his terminal. For displaying documents, common graphic spaces are used so that when one user opens a document in a common graphic space, the same document is simultaneously displayed on all terminals. The concept of a common space can also be applied to full-motion video so as to display the same facial images to all participants. EP-A-0 351 757 discloses a multipoint-and-multiconference system which allows a participant to take part in a plurality of conferences being held simultaneously, by optionally switching from one conference to another. According to the present invention, there is provided a multi-location television conference system having a plurality of television conference terminal units and comprising image distributing means for transmitting image data to each of said television conference terminal units for display thereon; characterised by speaking location detecting means for detecting a speaking location corresponding to sound signals that are output from sound input means of each of said television conference terminal units; and image combining means for designing a layout of a display area corresponding to the number of speaking locations for each television conference terminal unit and generating image data containing images of the speaking locations to be displayed in the designed display area of each television conference terminal unit when a plurality of speaking locations are detected by said speaking location detecting means; wherein said image distributing means transmits image data generated by said image combining means to each of said television conference terminal units. The present invention also embraces a multi-location control apparatus for use in the above system and comprising the speaking location detection means, image combining means, and image distributing means. Reference is made, by way of example, to the accompanying drawings in which: Fig. 1 is a schematic diagram showing overall construction of a multi-location television conference system; Fig. 2 is a schematic diagram for explaining the operation of an NS/PS designating mode; Fig. 3 is a block diagram showing a construction of a conventional multi-location television conference system; Fig. 4 is a block diagram showing an inner construction of a multi-location control apparatus having a conventional NS/PS designating mode; Fig. 5 is a block diagram showing the principle of construction of the present invention; Fig. 6 is a block diagram showing overall construction of a multi-location television conference system according to an embodiment of the present invention; Fig. 7 is a block diagram showing detailed construction of the multi-location conference system according to the embodiment; Fig. 8 is a block diagram for explaining a principle of operation of the embodiment; Fig. 9 is a schematic diagram for explaining display method in the case that speeches take place at four locations at the same time; Fig. 10 is a schematic diagram for explaining display method in the case that speeches take place at two locations at the same time; Fig. 11 is a schematic diagram for explaining display method in the case that a speech takes place at one location; Fig. 12 is a schematic diagram showing an example of transmitting method of an image signal from each television conference terminal unit to the multilocation control apparatus; Fig. 13 is a schematic diagram showing an example of generating method of an image signal displayed on four divided areas of one screen; Fig. 14 is a flow chart for explaining overall operation of the embodiment; Fig. 15 is a flow chart for explaining operation in the case that speeches take place at a plurality of locations at the same time; and Fig. 16 is a flow chart for explaining operation in the case that a speech takes place at one location. Fig. 1 is a block diagram showing the principle of construction according to the present invention. In this drawing, reference numerals 161-1, 161-2, 161-3 and 161-N are television conference terminal units that receive and transmit sound data and image data. The first aspect of the present invention is a multi-location control apparatus for use with a multi-location television conference system that has a plurality of multi-location television conference terminal units 161-i (where i = 1, 2, ... , and N) disposed at three or more locations, each of the television conference terminal units being adapted for transmitting and receiving sound data and image data, the multi-location control apparatus being adapted for receiving sound data and image data from all of the television conference terminal units 161-i and for transmitting sound data and image data to the television conference terminal units 161-i. The multi-location control apparatus 170 comprises speaking location detecting unit 171 for detecting a speaking location corresponding to sound signals that are output from sound input units of each of the television conference terminal units 161-i, image combining unit 172 for generating image data containing images of speaking locations when a plurality of speaking locations are detected by the speaking location detecting unit 171, and image distributing unit 173 for transmitting image data generated by the image combining unit 172 to each of the television conference terminal units 161-i. In the multi-location control apparatus, the speaking location detecting unit 171 detects occurrences of speaking locations with sound input signals received from the television conference terminal units 161-1, 161-2, ..., and 161-N. The image combining unit 172 divides and combines image signals of the speaking locations so as to generate an image signal that allows images of speaking locations to be displayed on divided screen areas of a monitor at a time. The image distributing unit 173 distributes the image signal to each of the television conference terminal units 161-i (where i = 1, 2, ... , and N). Thus, when there are a plurality of speaking locations, images of the speaking locations are displayed on monitor screen of each of the television conference terminal units 161-i. Corresponding to the number of speaking locations, the number of images of speaking locations displayed on each monitor varies. The image combining unit 172 may be adapted for generating image data of speaking locations detected by the speaking location detecting unit 171 for listening locations where speeches are not detected by the speaking location detecting unit 171, the image data being contained in one screen, and the image distributing unit 173 may be adapted for distributing the image data to television conference terminal units 161-i of the listening locations. In this case, for listening locations, the image combining unit 172 generates image data that contains only images of speaking locations in one screen. The image distributing unit 173 distributes the image data to terminal units 161-i at listening locations. Thus, when there are a plurality of speaking locations, images of the speaking locations are simultaneously displayed at terminal units 161-i at listening locations. In addition, the image combining unit 172 may be adapted for generating image data of other speaking locations and a former speaking location for each of the speaking locations, the image data being contained in one screen, and the image distributing unit 173 may be adapted for transmitting the image data to television conference terminal units 161-i of the speaking locations. In this case, for speaking locations, the image combining unit 172 generates image data that contains images of other speaking locations and an image of a former speaking location in one screen. The image distributing unit 173 distributes the image data to each of the speaking locations. Thus, each of the television conference terminal units 161-i at the speaking locations displays images of other speaking locations and an image of the former speaking location at a time. Fig. 6 is a schematic diagram showing an overall construction of a multi-location television conference system according to an embodiment of the present invention. In this drawing, a multi-location control apparatus 1100 is disposed in a center station. The multi-location control apparatus 1100 is connected to television conference terminal units 1200 (1200A, 1200B, 1200C, 1200D, and 1200E) of conference rooms disposed at five locations A, B, C, D, and E through a network such as ISDN or high speed digital dedicated line. Fig. 7 is a block diagram showing a detailed construction of the multi-location television conference system. Each of the television conference terminal units 1200A to 1200E comprises a plurality of microphones 1201, a microphone mixer 1202, a speaker 1203, a sound control unit 1204, a sound encoding and decoding unit (sound CODEC) 1205, a camera 1206, a monitor 1207, an image CODEC 1208, and a multiplexing and demultiplexing unit (MUX/DMUX) 1209. The microphones 1201 are directed to attendants in a conference room. The microphone mixer 1202 mixes outputs of the microphones 1201. The speaker 1203 outputs a sound of another television conference terminal unit 1200. The sound control unit 1204 performs an input/output sound switching operation, an echo removing operation, or the like so as to prevent the output sound of the speaker 1203 from entering the microphones 1201. The sound CODEC 1205 encodes sound data received from the sound control unit 1204 and decodes sound data sent to the sound control unit 1204. The camera 1206 photographs the entire scene of the conference room, attendants, and/or materials. The monitor 1207 displays images of other conference rooms received from other television conference terminal units 1200. The image CODEC 1208 encodes image data photographed by the camera 1206 and decodes encoded data to an image to be displayed on the monitor 1207. The MUX/DMUX unit 1209 multiplexes and demultiplexes an input signal and an output signal of the sound CODEC 1205 and the image CODEC 1208. The television conference terminal units 1200A to 1200E with the above-described construction are connected to the multi-location control apparatus 1100. The multi-location control apparatus 1100 comprises a multiplexing and demultiplexing (MUX/DMUX) unit 1101, a sound CODEC 1102, a sound detecting unit 1103, a sound mixer 1104, an image selecting unit 1105, and a screen combining unit 1106. The MUX/DMUX unit 1101 multiplexes sound data and image data received from the television conference terminal units 1200A to 1200E. In addition, the MUX/DMUX unit 1101 demultiplexes the multiplexed data into sound data and image data to be sent to the television conference terminal units 1200A to 1200E. The sound CODEC 1102 is connected to the MUX/DMUX unit 1101. The sound detecting unit 1103 detects occurrences of speeches at the locations A to E with levels of sound signals received from the sound CODECs 1102 of the television conference terminal units 1200A to 1200E. The sound mixer 1104 mixes the sound signals of the speaking locations detected by the sound detecting unit 1103 and sends the mixed sound signal to the speakers 1203 of the television conference terminal units 1200A to 1200E through the sound CODEC 1102 and the MUX/DMUX unit 1101. The image selecting unit 1105 receives sound signals from the sound detecting unit 1103, selects image data to be combined into one screen from image data of the locations A to E, and outputs image combining information. The image combining unit 1106 generates image data composed of a plurality of images of conference rooms received from the image selecting unit 1105 corresponding to the image combining information and distributes the combined image data to television conference terminal units 1200 of conference rooms at designated locations through the MUX/DMUX unit 1101. The sound detecting unit 1103 detects a maximum number of speaking locations (for example, four locations), where images thereof can be displayed on the monitors 1207 of the television conference terminal units 1200A to 1200E. The sound detecting unit 1103 detects whether or not a sound level of each location exceeds a predetermined threshold value. In addition, the sound detecting unit 1103 determines whether or not the number of speaking locations exceeds the maximum number of locations. When the number of speaking locations exceeds the maximum number of locations, the speaking locations with larger sound levels are selected for the maximum number of locations. Thus, the locations A to E are categorized as speaking locations and listening locations. The image selecting unit 1105 and the image combining unit 1106 combine image data of all the speaking locations that have been selected into image data of one screen. Image data displayed at each speaking location differs from image data displayed at each listening location. Fig. 8 shows input/output interface of image data and sound data between the multi-location control apparatus 1100 and each of the television conference terminal units 1200A to 1200E. In reality, as will be described later, an image that is output to each speaking location differs, location by location. Sound data that the sound mixer 1104 outputs to speaking locations differs from sound data that the sound mixer 1104 outputs to listening locations. Likewise, image data that the image combining unit 1106 outputs to the speaking locations differs from image data that the image combining unit 1106 outputs to the listening locations. The sound mixer 1104 mixes sounds corresponding to images of the locations A to E. The mixing operation of the sound mixer 1104 is based on image combining information received from the image selecting unit 1105. Next, an example of display method in the case that attendants speak at the locations A to E will be described. Fig. 9 shows display screens (monitor screens) on monitors 1207 of television conference terminal units 1200 in the case that attendants at four locations (in this case, locations A, B, C, and D) speak at the same time. Fig. 9 (a) shows a display screen at a listening location (in this case, location E). Fig. 9 (b) shows a display screen at a speaking location (in this case, location A). In this case, since there are four speaking locations, the monitors 1207 at the locations A to E each display four divided screen images. In other words, the monitors 1207 at the listening locations each display four divided screen images showing images of four locations A, B, C, and D. The images displayed on the monitors 1207 at the listening locations are the same. On the other hand, the monitor 1200 at the speaking location A displays images of three speaking locations B, C, and D and an image of the former speaking location F. As with the display screen of Fig. 9 (b), the monitors 1207 at the speaking locations B, C, and D displays images of speaking locations (other than the local location) and an image of the former speaking location E. Fig. 10 shows monitor screens in the case that attendants speak at two locations (in this case, locations A and B). In this case, since there are two speaking locations, the monitors 1207 each display divided screen images of the two speaking locations. As shown in Fig. 10 (b), the monitors 1207 at listening locations C, D, and E each display divided screen images of the speaking locations A and B. On the other hand, as shown in Fig. 10 (b), the monitor 1207 at the speaking location A displays divided screen images of the speaking location B and the former speaking location E. Likewise, the monitor 1207 at the speaking location B displays divided screen images of the other speaking location and the former speaking location E. Thus, in the case that there are two speaking locations, the monitor 1207 at a listening location displays divided screen images of two speaking locations. On the other hand, the monitor 1207 at the speaking location displays divided screen images of the other speaking location and the former speaking location. Fig. 11 shows display screens of monitors in the case that there is one speaking location (location A). In this case, the monitor screen is not divided. As shown in Fig. 11 (a), the monitors 1207 at listening locations B, C, D, and E each display an image of the speaking location A only. On the other hand, as shown in Fig. 11 (b), the monitor 1207 at the speaking location A displays an image of the former speaking location E only. Thus, in the case that there is only one speaking location, the monitors 1207 at the listening locations each display an image of the speaking location only. On the other hand, the monitor 1207 at the speaking location displays an image of the former speaking location only. However, in CCITT (Consultative Committee for International Telephony and Telegraphy) Recommendation H. 261, which is motion picture communication image encoding standard using primary subrate from 64 kb/s to 2 Mb/s, common intermediate format has been defined as image codec standard for visual telephone and television conference. In addition, for low-bit rate simple terminal units such as small visual telephones, QCIF (Quarter CIF) where the horizontal and vertical resolutions are the half of the CIF has been also defined. Fig. 12 is a schematic diagram for explaining a method for transmitting image data from the television conference terminal units 1200A to 1200E at locations A to E to the multi-location control apparatus 1100 with CIF. Fig. 13 is a schematic diagram for explaining a method for displaying images of four locations in four divided screen areas at a time as shown in Fig. 9 (a). The multi-location control apparatus 1100 is provided with a CIF/QCIF converter that converts image data of locations A, B, C, and D of CIF format into data of QCIF format. The image data of the QCIF format at the four locations are combined to one screen so that the images of the four locations A, B, C, and D shown in Fig. 9 (a) are displayed on one screen at a time. The combined data is sent to the television conference terminal unit 1200E at the location E. When there is one speaking location as shown in Fig. 11, the multi-location control apparatus 1100 selects and outputs the received image data of the CIF format to the television conference terminal units 1200 at the listening locations through the image selecting unit 1105 and the image combining unit 1106, not through the CIF/QCIF converter. Next, with reference to flow charts shown in Figs. 14 to 16, an image output process (image data transmitting process) of the multi-location control apparatus 1100 for the television conference terminal units 1200A to 1200E at the locations A to E will be described. Fig. 14 is a main flow chart showing the image output process. In this drawing, the sound detecting unit 1103 detects the number of speaking locations (at step S1). The multi-location control apparatus 1100 determines whether or not the number of speaking locations is one according to the detected result (at step S12). When there are a plurality of speaking locations (determined result at step S12 is NO), the multi-location control apparatus 1100 performs a multi-image output process that causes images of a plurality of locations to be displayed as divided screen images on the monitors 1207 of the television conference terminal units 1200 at the locations A to E (at step S13). When there is one speaking location (the determined result at step S12 is YES), the apparatus 1100 performs a single image output process that causes an image of one speaking location to be displayed on the monitors 1207 at the locations A to E (at step 14). Fig. 15 is a flow chart showing the multi-image output process (S13). In this process, images of a plurality of speaking locations are combined into one frame (at step S131). Thus, the images shown in Figs. 9 (a) and 10 (a) are formed. The apparatus 1100 determines whether or not the output destination of the image data is current speaking locations (at step S132). When the output destination is current speaking locations (determined result at step S132 is YES), the apparatus 1100 replaces image data of speaking locations with image data of the former speaking location (at step S133). Thus, the apparatus 1100 outputs (transmits) the divided screen image data to the current speaking locations (at step S134). Thus, when the speaking location is location A, the divided screen image data shown in Fig. 9 (a) or Fig. 10 (a) is replaced with the divided screen image data shown in Fig. 9 (b) or Fig. 10 (b), respectively. The apparatus 1100 outputs the divided screen image data to the television conference terminal unit 1200A at the location A. When the output destination at step S132 is listening locations rather than current speaking locations, the apparatus 1100 outputs (transmits) the combined image data (at step S131) to this listening locations (at step S135). Thus, the divided screen image data shown in Figs. 9 (a) or Fig. 10 (a) is sent to the television conference terminal unit 1200E at the location E, which is a listening location. Fig. 16 is a flow chart showing the single image output process S14. In this process, the apparatus 1100 determines whether or not the output destination (transmission destination) of the divided screen image data is current speaking locations (at step S141). When the output destination is current speaking locations (determined result is YES), the apparatus 1100 outputs (transmits) single image data that is image data of the former speaking location to the television conference terminal units 1200 at the current speaking locations (at step S142). Thus, the apparatus 1100 transmits the single image data of the former speaking location in the format shown in Fig. 11 (b) to for example the location A, which is a single speaking location. On the other hand, when the output destination is a listening location at step S141, the apparatus 1100 outputs (transmits) the single image data of the current speaking location to the television conference terminal unit 120 at the listening location (at step S143). Thus, when only the location A is a speaking location, the apparatus 1100 outputs (transmits) single image data of the current speaking location A in the format shown in Fig. 11 (a) to the listening locations B, C, D, and E. In this embodiment, the multi-location control apparatus 1100 detects speaking locations. However, it should be appreciated that each of the television conference terminal units 1200 may detect speaking attendants at respective locations and sends speech detecting data (along with sound level data if necessary) to the multi-location control apparatus 1100. According to the present invention, when speeches are detected at a plurality of locations, image data that contains images of these speaking locations in one screen is generated and distributed to each television conference terminal unit. Thus, when a discussion is performed at a plurality of locations, images of the speaking locations can be displayed at a time. In addition, the number of images of locations displayed on the screen varies as the number of speaking locations varies. Thus, images with reality can be displayed. Moreover, even if a plurality of speeches are made at the same time, since these locations are displayed on the same screen, speaking locations can be easily identified. At each listening location, images of only speaking locations are displayed. Thus, at each listening location, speaking locations can be immediately identified. At each speaking location, images of other speaking locations and an image of a former speaking location are displayed on the same screen. Thus, at each speaking location, other speaking locations can be easily identified. Since image data switched and selected is output to each television conference terminal unit independent from other television conference terminal units, at each television conference terminal unit, an image of a desired conference room can be selected without necessity to switch monitor images displayed at other television conference terminal units. In addition, images displayed at each television conference terminal unit are not switched by an operation at another conference room.

Claims: A multi-location television conference system having a plurality of television conference terminal units and comprising: image distributing means for transmitting image data to each of said television conference terminal units for display thereon; characterised by: speaking location detecting means for detecting a speaking location corresponding to sound signals that are output from sound input means of each of said television conference terminal units; and image combining means for designing a layout of a display area corresponding to the number of speaking locations for each television conference terminal unit and generating image data containing images of the speaking locations to be displayed in the designed display area of each television conference terminal unit when a plurality of speaking locations are detected by said speaking location detecting means; wherein said image distributing means transmits image data generated by said image combining means to each of said television conference terminal units. The system as set forth in claim 1, wherein said image combining means generates and transmits the image data of the speaking locations detected by said speaking location detecting means to ones of said television conference terminal units at listening locations where sound is not detected by said speaking location detecting means, the transmitted image data of all of the speaking locations being simultaneously displayed on a single screen of each of the television conference terminal units of the listening locations, and wherein said image distributing means distributes the image data of the speaking locations to the television conference terminal units of the listening locations. The system as set forth in claim 1 or 2, wherein said image combining means generates the image data of other speaking locations and a former speaking location for each of the speaking locations, the image data being contained in one screen of each speaking location, and wherein said image distribution means transmits the image data of the other speaking locations to television conference terminal units of the speaking locations. A multi-location control apparatus for use in the system as set forth in claim 1, 2, or 3 and comprising said speaking location detection means, said image combining means, and said image distributing means.

Inventors: HATANAKA MASANOBU, NATORI HIROAKI, OKAZAKI REIKO, SANO SHOICHI, TAKEI HITOSHI, TAMUKI SHOICHI, HATANAKA, MASANOBU, NATORI, HIROAKI, OKAZAKI, REIKO, SANO, SHOICHI, TAKEI, HITOSHI, TAMUKI, SHOICHI, Hatanaka, Masanobu, c/o FUJITSU LIMITED, Natori, Hiroaki, c/o FUJITSU LIMITED, Okazaki, Reiko, c/o FUJITSU LIMITED, Sano, Shoichi, c/o FUJITSU LIMITED, Takei, Hitoshi, c/o FUJITSU LIMITED, Tamuki, Shoichi, c/o FUJITSU LIMITED
Applicants: FUJITSU LTD, FUJITSU LIMITED
Application year: 1994
Main classification: H04N7
IPC codes: H04N7, H04M3